The PSU looks like it is an obsolete design (note the really heavy 5 volt rail) dressed up with passive PFC. And 34 amps, even if that is the maximum 12 volt current, is
light for a 550 watt PSU. A 450 watt Corsair produces 33 amps. A 550 watt Corsair produces 41 amps.
One way to look at it is: If your PSU wasn't strong enough, then it shouldn't even POST...
Not exactly true. While the system is POST'ing, it's under a minimal load and the graphics card is loafing along under a 2D load. Even in an older video card, going to a 3D gaming load will double the power it consumes.
If your system is resetting/rebooting, you probably have one or more of the following problems:
1. Unstable overclock. I don't like overclocking graphics cards. The temps run too high anyway.
2. Unstable drivers.
3. Inadequate 12 volt power.